Hydrazine hydrate (1:1) → 5-phenoxymethyl-1H-pyrazole-3-carboxylic acid ethyl ester

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Reaction Steps

Hydrazine hydrate (0.197 mL, 4.06 mmol) was added to a stirring room temperature solution of 40 (1.0163 g, 4.06 mmol) in EtOH (4.1 mL, 1 M) under N2. The reaction was then heated to reflux until judged complete by HPLC. The reaction was concentrated and purified by silica gel chromatography (Combiflash column, 92:4:4 Hexanes:CH2Cl2: 2N NH3 in EtOH): Only pure fractions were combined and concentrated to obtain 0.5474 g (54.7%) of 41. 1H (CDCl3, 400 MHz): δ 12.12 (1H, broad s), 7.28 (2H, t, J=7.8 Hz), 7.01-6.94 (3H, m), 6.91 (1H, s), 5.17 (2H, s), 4.36 (2H, q, J=7.0 Hz), 1.36 (3H, t, J=7.1 Hz) ppm. Partial 13C (CDCl3, 100 MHz): δ 158.11, 129.48, 121.26, 114.71, 107.83, 62.61, 61.31, 14.17 ppm. HPLC: 9.505 min.

Provenance & Evidence